Climate killer cow: Cattle produce the potent greenhouse gas methane, but this output differs depending on the animal and feed. That is why researchers have now developed a new method with which farmers can determine the individual methane production of their cows using the characteristics of the milk. This makes it easier to reduce the output by changing the feed.
Cows not only provide milk and meat, but also produce methane (CH4) during their digestion, which is released through “burping” and through manure and slurry. Methane is a climate-relevant greenhouse gas that has a warming potential that is around 20 times higher than that of carbon dioxide (CO2). According to current estimates by the Federal Environment Agency, the methane emissions of dairy cows with over 14,000 kilotons of CO2 equivalents contribute to around 20 percent of the total greenhouse gas emissions from German agriculture.
Methane production varies from cow to cow
But not every cattle emits the same amount of methane. The amount depends, among other things, on the feed and breed and can vary from animal to animal between 400 and 700 liters per day. However, this also means that methane emissions from cattle farming could be reduced in a targeted manner, for example through targeted feeding methods – if the livestock farmers knew how much greenhouse gas their cows produce depending on the feed. However, measuring this value in the barn or in the pasture is very difficult and not particularly pleasant for the cows.
That is why scientists around Stefanie Engelke from the Leibniz Institute for Farm Animal Biology in Dummerstorf have now developed a method to calculate the methane emissions of a dairy cow based on its milk. To obtain reference values, they first measured the methane emissions of 20 Holstein dairy cows in a respiration chamber that were fed with feed made from maize or grass silage and with and without flaxseed.
To find out whether these values can be linked to the properties of the milk, the researchers then determined the milk fat content using spectroscopy and the milk yield of the test cows. “No additional equipment or expenses are necessary for this, because these data are collected in many test laboratories in Germany for the monthly milk control from infrared spectroscopic measurements,” explains Engelke’s colleague Cornelia Metges. Using all the measurement data, the team then set up an equation that links milk characteristics and methane emissions.
Milk reveals methane emissions – and makes countermeasures easier
It was shown: “In our series of measurements we were able to clearly establish and scientifically prove that a realistic estimate of methane emissions can be determined from the milk fat composition and the amount of milk,” says Metges. “If this data is available to the dairy farmer, the methane emissions could be calculated for each individual animal using the patented equation.” Because the milk yield is included in the formula, the results of this method also better reflect the differences in feeding than other methane estimation methods, as the researcher explains.
In the opinion of the research team, this method opens up new possibilities for reducing methane emissions in cattle farming. Farmers can now easily determine how much greenhouse gas their cows are producing. If the output is relatively high, you can try to take targeted countermeasures through feeding. “Since feeding plays an important role in the emission of methane from cattle, a sustainable reduction can also be achieved through appropriate feeding management,” says Metges. “However, there are no business incentives for farmers to become active here. If they have to cope with ever more costly requirements with falling revenues, ultimately nothing will change. ”This is also a question of politics.
Source: Leibniz Institute for Farm Biology (FBN), Article: Agronomy for Sustainable Development, doi: 10.1007 / s13593-018-0502-x